The functional equation f(z)~n+g(z)~n=1 can be interpreted as the Fermat-type equations over function field. In this paper, by using Nevanlinna theory of meromorphic functions, we investigate the existence of meromorphic solutions of hyper-order strictly less than 1 to the Fermat-type functional equation(a0f(z)+a1f(z+c))3+(b0f(z)+b1f(z+c))3= eαz+β,where a0, a1, b0, b1, α, β, c are complex constants and c≠0.